3,4-diaminobenzenesulfonic acid (DBSA), also known as orthaminic acid, is a useful compound having applications in the fields of crop protection, pharmaceutical preparation, cosmetics, and dyes. Particularly for pharmaceutical preparations and in cosmetics, a strong need exists for having highly pure DBSA. Common routes for synthesizing DBSA involve the sulfonation of 1,2-diaminobenzene (DAB). However, known large-scale sulfonation processes for DAB suffer from the disadvantages of inadequate yield, impure sulfonation products such as doubly sulfonated analogs of DBSA, costly apparatus requiring extreme pressure-resistance and corrosion-resistance in the presence of acids such as hydrochloric acid and sulfuric acid, and needs for energy-inefficient distillation steps.